Clofarabine targets the large subunit (?) of human ribonucleotide reductase in live cells by assembly into persistent hexamers.

ABSTRACT: Clofarabine (ClF) is a drug used in the treatment of leukemia. One of its primary targets is human ribonucleotide reductase (hRNR), a dual-subunit, (?(2))(m)(?(2))(n), regulatory enzyme indispensable in de novo dNTP synthesis. We report that, in live mammalian cells, ClF targets hRNR by converting its ?-subunit into kinetically stable hexamers. We established mammalian expression platforms that enabled isolation of functional ? and characterization of its altered oligomeric associations in response to ClF treatment. Size exclusion chromatography and electron microscopy documented persistence of in-cell-assembled-?(6). Our data validate hRNR as an important target of ClF, provide evidence that in vivo ?'s quaternary structure can be perturbed by a nonnatural ligand, and suggest small-molecule-promoted, persistent hexamerization as a strategy to modulate hRNR activity. These studies lay foundations for documentation of RNR oligomeric state within a cell.

SUBMITTER: Aye Y 

PROVIDER: S-EPMC3408589 | biostudies-literature | 2012 Jul

REPOSITORIES: biostudies-literature